Raju was very interested in coordinates. He knew that the location of each point on the Earth had a unique coordinate noting its latitudes and longitudes. He had read that there were people who tried to reach the point of concurrence ie the point of intersection of a latitude with a longitude. In class the next day, he asked the teacher, “Teacher why do some people try and reach the point of concurrence of latitude and longitude? What is so special about it?”
The teacher explained, “Considering the expanse of the Earth can you imagine how much area will be enclosed by the quadrilateral formed by the two successive latitudes and longitudes? That means the area enclosed between the equator and the latitude one degree north and Prime Meridian and the one degree east longitude? It will be huge. But as one moves towards the poles this area becomes lesser and will have only a point at the pole which is 90 degrees north latitude and point of intersection of all the longitudes. So don’t you thing it’s interesting to reach that exact point?”
She continued, “Many such points will be in the middle of the oceans and many will be on difficult terrains, some will be within a building while some may be in a river, some may be in thick forests, some right in the middle of the road. It gives a feeling of achievement if you can manage to reach such a point. Now it has become even easier due to GPS. Now we can easily know our exact location in terms of latitude and longitude using our mobile phones.”
“Now, there are some more interesting things about the rotation and the way we move towards either poles,” continued the teacher.
“Tell us, teacher,” chorused the students.
They couldn’t contain their excitement as the teacher began to speak. “What is the direction of rotation of the Earth,” she asked.
“From west to east,” the students answered in unison. “That is why the sun appears to move from east to west.”
The teacher was pleased. “Good. Now imagine you are at any point on the Earth except the poles. If you’re facing the North Pole, the east will be on our right but if you face the South Pole the east will be on our left. But once you reach the poles there is no east and no west as it is just a point where all the meridians or the longitudes meet,” said the teacher.
The students were amazed. “So when we are exactly at the pole, we are an extension of the pole. And we rotate with the axis,” said Raju.
“Also another very interesting fact is that all the longitudes are of the exact length, but latitudes get smaller and smaller as we move away from the equator, which is the longest latitude. We will see more interesting facts in our next class,” she concluded.
(Writer is a mechanical engineer and runs a hands-on science activity centre at Margao)